Prevulcanization inhibitors having a characteristic nucleus of ##STR2## are well known and widely used in the rubber industry. Some workers object to a malodorous quality associated with inhibitor use. The objectionable odor is not necessarily associated with the inhibitor alone, but seems to develop as a consequence of contact with the skin or mucous membrane. Moreover, the bad odor is not always apparent immediately upon exposure, but generally develops several minutes after exposure. Since the unpleasant odor or taste is not immediately obvious, it is sometimes called "after-odor", i.e., an odor which arises "after" use of the inhibitor.